CN115567027B - Transducer, surface acoustic wave resonator, method of forming the same, and filter - Google Patents
Transducer, surface acoustic wave resonator, method of forming the same, and filter Download PDFInfo
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- CN115567027B CN115567027B CN202211366349.8A CN202211366349A CN115567027B CN 115567027 B CN115567027 B CN 115567027B CN 202211366349 A CN202211366349 A CN 202211366349A CN 115567027 B CN115567027 B CN 115567027B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14544—Transducers of particular shape or position
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02818—Means for compensation or elimination of undesirable effects
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02818—Means for compensation or elimination of undesirable effects
- H03H9/02897—Means for compensation or elimination of undesirable effects of strain or mechanical damage, e.g. strain due to bending influence
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
- H03H9/6489—Compensation of undesirable effects
Abstract
A transducer device, a surface acoustic wave resonator device, a method of forming the same, and a filter device, wherein the surface acoustic wave resonator device includes: a piezoelectric substrate; a transduction device on a piezoelectric substrate, the transduction device comprising: the electrode strips are arranged in parallel along a first direction, each electrode strip comprises a first layer and a second layer positioned above the first layer, and the average diameter of first grains in the first layer is smaller than that of second grains in the second layer. The performance of the surface acoustic wave resonator device is improved.
Description
Technical Field
The present invention relates to the field of semiconductors, and more particularly, to a transducer, a surface acoustic wave resonator, a method of forming the same, and a filter.
Background
With the development of communication technology, filters have been widely used in various communication electronic devices.
Currently, commercial filters mainly include a surface acoustic wave (Surface Acoustic Wave, abbreviated as SAW) filter, a bulk acoustic wave (Bulk Acoustic Wave, abbreviated as BAW) filter, a low-temperature co-fired ceramic (Low Temperature Co-fired Ceramics, abbreviated as LTCC) filter, and the like. The surface acoustic wave filter has the advantages of good insertion loss, small area and the like, and is widely applied to consumer electronic terminals such as mobile phones and the like.
However, the reliability of the surface acoustic wave filter at high power has yet to be improved.
Disclosure of Invention
The invention solves the technical problem of providing a transducer, a surface acoustic wave resonator, a forming method thereof and a filter device so as to improve the reliability of a surface acoustic wave filter under high power.
In order to solve the above technical problems, the present invention provides a transducer device, including: the electrode strips are arranged in parallel along a first direction, each electrode strip comprises a first layer and a second layer positioned above the first layer, and the average diameter of first grains in the first layer is smaller than that of second grains in the second layer.
Optionally, the yield strength of the first layer material is greater than the yield strength of the second layer material.
Optionally, the resistivity of the first layer material is greater than the resistivity of the second layer material.
Optionally, the material of the first layer includes an aluminum-neodymium alloy, wherein the atomic percentage content of neodymium atoms in the aluminum-neodymium alloy is 1% -8%.
Optionally, the material of the second layer includes an aluminum-copper alloy or aluminum, wherein the atomic percentage content of copper atoms in the aluminum-copper alloy is 0.5% -4%.
Optionally, the electrode strip further includes: and a third layer on the second layer for inhibiting electromigration, the third layer material having a density greater than the second layer material.
Optionally, the material of the third layer includes a metal or a metal nitride; wherein the metal comprises titanium, nickel, molybdenum, copper or platinum; the metal nitride comprises titanium nitride.
Optionally, the thickness of the first layer is less than or equal to 50% of the thickness of the electrode strip.
Optionally, the electrode strip further includes: a first bonding layer between the first layer and the second layer.
Optionally, the material of the first bonding layer includes a metal or a metal nitride; wherein the metal comprises titanium, titanium tungsten alloy or nichrome; the metal nitride comprises titanium nitride.
Correspondingly, the technical scheme of the invention also provides a surface acoustic wave resonance device, which comprises: a piezoelectric substrate; and a transduction device positioned on the piezoelectric substrate.
Optionally, the electrode strip further includes: and a second bonding layer located between the piezoelectric substrate and the first layer.
Optionally, the material of the second bonding layer includes a metal or a metal nitride; wherein the metal comprises titanium, titanium tungsten alloy or nichrome; the metal nitride comprises titanium nitride.
Correspondingly, the technical scheme of the invention also provides a filtering device, which comprises: a plurality of surface acoustic wave resonators.
Correspondingly, the technical scheme of the invention also provides a method for forming the surface acoustic wave resonance device, which comprises the following steps: providing a piezoelectric substrate;
optionally, a transduction device is formed on the piezoelectric substrate, and the transduction device includes: a plurality of electrode bars disposed in parallel along a first direction parallel to a surface of the piezoelectric substrate, wherein the electrode bars comprise: a first layer and a second layer over the first layer, the average diameter of first grains in the first layer being smaller than the average diameter of second grains in the second layer.
Optionally, the yield strength of the first layer of material is greater than the second yield strength of the second layer of material.
Optionally, the resistivity of the first layer material is greater than the resistivity of the second layer material.
Optionally, forming the plurality of electrode strips includes: forming a first material layer over a piezoelectric substrate; forming a second material layer over the first material layer; and patterning the second material layer and the first material layer to form a plurality of electrode strips.
Optionally, forming the plurality of electrode strips further includes: forming a first bonding material layer before forming the second material layer, wherein the first bonding material layer is positioned on the first material layer, and the second material layer is positioned on the first bonding material layer; patterning the first bonding material layer to form a first bonding layer between the first layer and the second layer.
Optionally, forming the plurality of electrode strips further includes: forming a second bonding material layer before forming the first material layer, wherein the bonding material layer is positioned on the piezoelectric substrate, and the first material layer is positioned on the second bonding material layer; and patterning the second bonding material layer to form a second bonding layer between the first layer and the piezoelectric substrate.
Optionally, forming the plurality of electrode strips further comprises: a third layer is formed on the second layer for inhibiting electromigration, the third layer material having a density greater than the second layer material.
Optionally, forming the third layer includes: forming a third material layer before patterning the second material layer and the first material layer, wherein the third material layer is positioned on the second material layer; patterning the third material layer to form a third layer on the second layer.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
according to the technical scheme, the transduction device comprises a plurality of electrode strips, wherein the electrode strips comprise a first layer and a second layer arranged on the first layer, the average diameter of first crystal grains in the first layer is smaller than that of second crystal grains in the second layer, and therefore the yield strength of a first layer material is larger than that of a second layer material. The maximum stress is generated at the junction of the transducer and the piezoelectric substrate, namely the first layer, when the surface acoustic wave resonance device vibrates, so that the yield strength of the first layer material is larger, the whole yield strength of the transducer can be improved, the conditions of cavities and protrusions caused by stress extrusion generated by vibration are reduced, the inhibition performance of the transducer on vibration migration is enhanced, and the reliability of the transducer and the power tolerance of the surface acoustic wave resonance device are improved.
Further, decreasing the average diameter of the first grains in the first layer increases the resistivity of the first layer material, so the second layer material adopts a lower resistivity material to balance the overall resistivity of the transducer, i.e., has less impact on the overall resistivity of the transduction device.
Further, the electrode strip further includes: and a third layer positioned on the surface of the second layer, wherein the third layer can inhibit electromigration of aluminum atoms in the material of the second layer on the surface.
Drawings
FIGS. 1 and 2 are schematic diagrams of the structure of a resonant device in one embodiment;
FIGS. 3 to 5 are schematic views illustrating a process of forming a resonant device according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a resonant device according to another embodiment of the present invention;
fig. 7 is a schematic diagram of stress distribution of a resonant device according to an embodiment of the invention.
Detailed Description
As described in the background art, the performance of the surface acoustic wave filter has yet to be improved. The analysis will now be described with reference to specific examples.
Fig. 1 and 2 are schematic structural views of a resonant device in an embodiment.
Referring to fig. 1 and 2, fig. 1 is a top view of fig. 2, fig. 2 is a schematic cross-sectional structure of fig. 1 along a cross-sectional line AA1, and the resonant device includes: a substrate 100; a transduction device located on a substrate 100, the transduction device comprising: a first bus bar 107 and a second bus bar 108 extending in a first direction X parallel to the surface of the substrate 100, the first bus bar 107 and the second bus bar 108 being parallel to each other; a plurality of first electrode bars 102 connected to the first bus bar 107, the plurality of first electrode bars 102 being arranged in parallel along a first direction X; a plurality of second electrode bars 103 connected to the second bus bar 108, wherein the plurality of second electrode bars 103 are arranged in parallel along a first direction X, the first electrode bars 102 and the second electrode bars 103 are alternately arranged along the first direction X, and the projection parts of the first electrode bars 102 and the second electrode bars 103 in the first direction X are overlapped; a plurality of third electrode bars 105 connected to the first bus bars 107, the third electrode bars 105 being located between adjacent first electrode bars 102, and a central axis of the third electrode bars 105 in a second direction Y parallel to a surface of the substrate 100 being coincident with a central axis of the second electrode bars 103 in the second direction Y, a gap being provided between the third electrode bars 105 and the second electrode bars 103; a plurality of fourth electrode bars 106 connected to the second bus bars 108, the fourth electrode bars 106 being located between adjacent second electrode bars 103, and a central axis of the fourth electrode bars 106 in the second direction Y coinciding with a central axis of the first electrode bars 102 in the second direction Y, a gap being provided between the fourth electrode bars 106 and the first electrode bars 102; an adhesion layer 101 between the first electrode bar 102 and the substrate 100, and between the second electrode bar 103 and the substrate 100.
The transducer is an interdigital transducer structure of the surface acoustic wave filter, the interdigital transducer of the surface acoustic wave filter is easy to fail under high power, and the failure mode mainly comprises two modes of electromigration and vibration migration. The material of the interdigital transducer is typically aluminum, and the electromigration is the migration of aluminum atoms in the crystal grains under high current conditions, forming protrusions 104 (as shown in fig. 1) and voids, the protrusions 104 causing the interdigital electrodes of the interdigital transducer to short circuit and thereby cause failure. The vibration migration means that when the interdigital transducer works in the surface acoustic wave filter, the high-frequency vibration of the interdigital electrode extrudes metal of the interdigital transducer, and the extrusion forms a protrusion 104 and a cavity on the surface, and the protrusion 104 causes the finger of the interdigital transducer to be short-circuited to cause failure.
In order to solve the problems, the technical scheme of the invention provides a transduction device, a surface acoustic wave resonance device, a forming method of the transduction device and a filtering device, wherein the transduction device comprises a plurality of electrode strips, the electrode strips comprise a first layer and a second layer positioned on the first layer, the average diameter of crystal grains in the first layer is smaller than the average diameter of crystal grains in the second layer, and therefore the yield strength of a first layer material is larger than that of a second layer material. The maximum stress is generated at the junction of the transducer and the piezoelectric substrate, namely the first layer, when the surface acoustic wave resonance device vibrates, so that the yield strength of the first layer material is larger, the whole yield strength of the transducer can be improved, the conditions of cavities and protrusions caused by stress extrusion generated by vibration are reduced, the inhibition performance of the transducer on vibration migration is enhanced, and the reliability of the transducer and the power tolerance of the surface acoustic wave resonance device are improved.
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 3 to 5 are schematic structural views illustrating a process of forming a resonant device according to an embodiment of the present invention.
Referring to fig. 3, a piezoelectric substrate 200 is provided.
The material of the piezoelectric substrate 200 includes a piezoelectric material including Lithium Tantalate (LT), lithium Niobate (LN), quartz, aluminum nitride, zinc oxide, gallium nitride, or lead zirconate titanate piezoelectric ceramic (PZT).
Next, a transduction device is formed on the piezoelectric substrate 200, the transduction device including: the electrode strips are arranged in parallel along a first direction, each electrode strip comprises a first layer and a second layer positioned above the first layer, and the average diameter of first grains in the first layer is smaller than that of second grains in the second layer. The process of forming the transducer device is shown in fig. 3 to 5.
With continued reference to fig. 3, a second bonding material layer 201 is formed on the piezoelectric substrate 200; forming a first material layer 202 on the second bonding material layer 201; forming a first bonding material layer 203 on the first material layer 202; a second material layer 204 is formed on the first bonding material layer 203.
The material of the first bonding material layer 203 includes a metal or a metal nitride, and the metal includes titanium, titanium tungsten alloy or nichrome; the metal nitride comprises titanium nitride. The first bonding material layer 203 serves to increase the bonding stability between the first material layer 202 and the second material layer 204. The first bonding material layer 203 is used for forming a first bonding layer 207 later.
In other embodiments, the first bonding material layer may not be formed.
The material of the second bonding material layer 201 includes a metal or a metal nitride, and the metal includes titanium, titanium tungsten alloy or nichrome; the metal nitride comprises titanium nitride. The second bonding material layer 201 serves to increase the bonding stability between the first material layer 202 and the piezoelectric substrate 200. The second bonding material layer 201 is used for forming the second bonding layer 205 later.
In other embodiments, the second bonding material layer may not be formed.
The first material layer 202 is used for subsequent formation of a first layer 206, the second material layer 204 is used for subsequent formation of a second layer 208, and the yield strength of the material of the first material layer 202 is greater than the yield strength of the material of the second material layer 204.
In this embodiment, the average diameter of the grains of the first material layer 202 is smaller than the average diameter of the grains of the second material layer 204.
In this embodiment, the resistivity of the first material layer 202 is greater than the resistivity of the second material layer 204 because the smaller the average grain size is. Reducing the average diameter of the grains in the first material layer 202 increases the resistivity of the first layer material, so the second layer material adopts a lower resistivity material to balance the overall resistivity of the transducer, i.e., has less impact on the overall resistivity of the transducer.
In this embodiment, the material of the first material layer 202 includes an aluminum neodymium alloy.
In this embodiment, the material of the first material layer 202 includes an aluminum-neodymium alloy, and the atomic percentage content of neodymium atoms in the aluminum-neodymium alloy material is 1% -8%. The content of neodymium atoms reduces the average diameter of the aluminum-neodymium alloy grains.
The material of the second material layer 204 includes aluminum copper alloy or aluminum.
In this embodiment, the material of the second material layer 204 includes an aluminum-copper alloy, and the atomic percentage content of copper atoms in the aluminum-copper alloy material is 0.5% -4%. Copper atoms of the aluminum-copper alloy can be precipitated in the boundaries of subsequently formed grains of the second layer material, so that the atoms of the second layer material are prevented from diffusing among the grains, the formation of protrusions and holes is reduced, and the inefficacy caused by electromigration can be effectively inhibited. Thereby improving the reliability of the transducer.
Referring to fig. 4 and 5, fig. 4 is a top view of fig. 5, fig. 5 is a schematic cross-sectional structure along a cross-sectional line BB1 of fig. 4, and the second material layer 204, the first bonding material layer 203, the second bonding material layer 201, and the first material layer 202 are patterned to form a transducer device on the piezoelectric substrate 200.
The method of patterning the second material layer 204, the first bonding material layer 203, the second bonding material layer 201, and the first material layer 202 includes: forming a patterned photoresist layer (not shown) over the second material layer 204; etching the second material layer 204, the first bonding material layer 203, the second bonding material layer 201, and the first material layer 202 with the patterned photoresist layer as a mask to form the transduction device, wherein the transduction device comprises: a plurality of electrode strips disposed in parallel along a first direction parallel to a surface of the piezoelectric substrate 200, the electrode strips including a first layer 206 and a second layer 208 over the first layer 206, an average diameter of first grains in the first layer 206 being smaller than an average diameter of second grains in the second layer 208.
The process of etching the second material layer 204, the first bonding material layer 203, the second bonding material layer 201 and the first material layer 202 includes a dry etching process, and the dry etching process has good etching precision, so that a transduction device meeting the requirement can be formed.
With continued reference to fig. 4, the structure of the transducer includes: a first bus bar 212 and a second bus bar 213 extending in a first direction X parallel to a surface of the piezoelectric substrate 200, the first bus bar 212 and the second bus bar 213 being parallel to each other; a plurality of first electrode bars 221 connected to the first bus bar 212, the plurality of first electrode bars 221 being arranged in parallel along a first direction X; the second bus bars 213 are connected to a plurality of second electrode bars 220, the plurality of second electrode bars 220 are arranged in parallel along a first direction X, the first electrode bars 221 and the second electrode bars 220 are alternately arranged along the first direction X, and the projection portions of the first electrode bars 221 and the second electrode bars 220 in the first direction X overlap.
In this embodiment, the structure of the transducer device further includes: a plurality of third electrode bars 210 connected to the first bus bar 212, the third electrode bars 210 being located between adjacent first electrode bars 221, and a central axis of the third electrode bars 210 in a second direction Y parallel to a surface of the piezoelectric substrate 200 being coincident with a central axis of the second electrode bars 220 in the second direction Y, and a gap being provided between the third electrode bars 210 and the second electrode bars 220; the fourth electrode strips 211 are connected with the second bus bars 213, the fourth electrode strips 211 are located between the adjacent second electrode strips 220, the central axis of the fourth electrode strips 211 in the second direction Y coincides with the central axis of the first electrode strips 221 in the second direction Y, and a gap is formed between the fourth electrode strips 211 and the first electrode strips 221.
In other embodiments, the third electrode bar and the fourth electrode bar may not be formed.
With continued reference to fig. 5 and 7, fig. 7 is a schematic diagram of stress distribution of the filter, and the materials of the transducer include: a first layer 206 on the piezoelectric substrate 200, and a second layer 208 on the first layer 206, the materials of the first layer 206 and the second layer 208 comprising a metal, the yield strength of the first layer 206 material being greater than the yield strength of the second layer 208 material.
Since the maximum stress occurs at the boundary between the transducer and the piezoelectric substrate 200 (region a shown in fig. 7) when the saw resonator vibrates, that is, the maximum stress occurs at the first layer 206, the yield strength of the material of the first layer 206 is greater, so that the yield strength of the whole transducer can be improved, the conditions of voids and protrusions caused by stress extrusion generated by vibration are reduced, the inhibition of the transducer to vibration migration is enhanced, and the reliability of the transducer and the power tolerance of the saw resonator are improved.
In this embodiment, the first average grain diameter of the first layer 206 material is smaller than the second average grain diameter of the second layer 208 material. The average diameter of the first crystal grains of the material of the first layer 206 is smaller, so that the continuity of interfaces among the crystal grains can be reduced, meanwhile, the crystal grain size of the material of the first layer 206 is reduced, the yield strength of the material of the first layer 206 can be improved, the overall yield strength of the transduction device is further improved, the situation that the material of the transduction device is extruded to cause cavities and protrusions by stress generated when the material of the transduction device is vibrated is reduced, and the inhibition of the transduction device on vibration migration is enhanced. Thereby improving the reliability of the transducer device and the power tolerance of the surface acoustic wave resonator device.
In this embodiment, the first layer 206 and the piezoelectric substrate 200 have a second bonding layer 205 therebetween, and the first layer 206 and the second layer 208 have a first bonding layer 207 therebetween.
In other embodiments, the first layer and the substrate can have no second bonding layer therebetween, and the first layer and the second layer can have no first bonding layer therebetween.
In this embodiment, the thickness of the first layer 206 is less than or equal to 50% of the thickness of the electrode strip. So that the transduction device does not increase the resistivity of the transduction device due to the too thick first layer 206 while enhancing the inhibition of vibration migration, thereby affecting the performance of the transduction device.
Accordingly, in an embodiment of the present invention, a transducer is provided, please continue to refer to fig. 4 and fig. 5, which includes:
a plurality of electrode bars, a plurality of the electrode bars are arranged in parallel along a first direction X, the electrode bars include a first layer 206 and a second layer 208 located above the first layer 206, and an average diameter of first grains in the first layer 206 is smaller than an average diameter of second grains in the second layer 208.
In this embodiment, the yield strength of the first layer 206 material is greater than the yield strength of the second layer 208 material.
In this embodiment, the resistivity of the material of the first layer 206 is greater than the resistivity of the material of the second layer 208.
In this embodiment, the material of the first layer 206 includes an aluminum-neodymium alloy, where the content of atomic percentage of neodymium atoms in the aluminum-neodymium alloy is 1% -8%.
In this embodiment, the material of the second layer 208 includes an aluminum-copper alloy or aluminum, where the atomic percentage content of copper atoms in the aluminum-copper alloy is 0.5% -4%.
In this embodiment, the thickness of the first layer 206 is less than or equal to 50% of the thickness of the electrode strip.
In this embodiment, the electrode strip further includes: a first bonding layer 207 is located between the first layer 206 and the second layer 208.
In this embodiment, the material of the first bonding layer 207 includes a metal or a metal nitride; wherein the metal comprises titanium, titanium tungsten alloy or nichrome; the metal nitride comprises titanium nitride.
Correspondingly, in the embodiment of the present invention, a surface acoustic wave resonator is further provided, please continue to refer to fig. 4 and fig. 5, which includes:
a piezoelectric substrate 200;
a transduction device on the piezoelectric substrate 200, the transduction device comprising: a plurality of electrode bars, a plurality of the electrode bars are arranged in parallel along a first direction X, the electrode bars include a first layer 206 and a second layer 208 located above the first layer 206, and an average diameter of first grains in the first layer 206 is smaller than an average diameter of second grains in the second layer 208.
In this embodiment, the yield strength of the first layer 206 material is greater than the yield strength of the second layer 208 material.
In this embodiment, the resistivity of the material of the first layer 206 is greater than the resistivity of the material of the second layer 208.
In this embodiment, the material of the first layer 206 includes an aluminum-neodymium alloy, where the content of neodymium atoms in the aluminum-neodymium alloy material is 1% -8% by atom.
In this embodiment, the material of the second layer 208 includes an aluminum-copper alloy or aluminum, where the atomic percentage content of copper atoms in the aluminum-copper alloy material is 0.5% -4%.
In this embodiment, further comprising: a second bonding layer 205 located between the piezoelectric substrate 200 and the first layer 206.
In this embodiment, the material of the second bonding layer 205 includes a metal or a metal nitride, and the metal includes titanium, titanium tungsten alloy, or nichrome; the metal nitride comprises titanium nitride.
In this embodiment, further comprising: a first bonding layer 207 located between the first layer 206 and the second layer 208.
In this embodiment, the material of the first bonding layer includes a metal or metal nitride, and the metal includes titanium, titanium tungsten alloy or nichrome; the metal nitride comprises titanium nitride.
In this embodiment, the structure of the transducer includes: a first bus bar 212 and a second bus bar 213 extending in a first direction X parallel to a surface of the piezoelectric substrate 200, the first bus bar 212 and the second bus bar 213 being parallel to each other; a plurality of first electrode bars 221 connected to the first bus bar 212, the plurality of first electrode bars 221 being arranged in parallel along a first direction X; the second bus bars 213 are connected to a plurality of second electrode bars 220, the plurality of second electrode bars 220 are arranged in parallel along a first direction X, the first electrode bars 221 and the second electrode bars 220 are alternately arranged along the first direction X, and the projection portions of the first electrode bars 221 and the second electrode bars 220 in the first direction X overlap.
In this embodiment, the thickness of the first layer 206 is less than or equal to 50% of the thickness of the first electrode strips 221 and the second electrode strips 220.
In this embodiment, the structure of the transducer device further includes: a plurality of third electrode bars 210 connected to the first bus bar 212, the third electrode bars 210 being located between adjacent first electrode bars 221, and a central axis of the third electrode bars 210 in a second direction Y parallel to a surface of the piezoelectric substrate 200 being coincident with a central axis of the second electrode bars 220 in the second direction Y, and a gap being provided between the third electrode bars 210 and the second electrode bars 220; the fourth electrode strips 211 are connected with the second bus bars 213, the fourth electrode strips 211 are located between the adjacent second electrode strips 220, the central axis of the fourth electrode strips 211 in the second direction Y coincides with the central axis of the first electrode strips 208 in the second direction Y, and a gap is formed between the fourth electrode strips 211 and the first electrode strips 221.
In other embodiments, the transduction structure can exclude the third electrode stripe and the fourth electrode stripe.
In this embodiment, the material of the piezoelectric substrate 200 includes a piezoelectric material including lithium tantalate, lithium niobate, quartz, aluminum nitride, zinc oxide, gallium nitride, or lead zirconate titanate piezoelectric ceramic.
Correspondingly, the embodiment of the invention also provides a filter formed by the surface acoustic wave resonant devices shown in fig. 4 and 5.
Fig. 6 is a schematic structural diagram of a resonant device according to another embodiment of the present invention.
Referring to fig. 6, fig. 6 is a schematic structural diagram based on fig. 5, and the difference between the structure of the resonant device in fig. 6 and the resonant device in fig. 5 is that: the electrode strip further comprises: a third layer 301 over the second layer 208 for inhibiting electromigration, the third layer 301 material having a density greater than the density of the second layer 208 material.
The forming method of the third layer 301 includes: forming a third material layer (not shown) on the surface of the second material layer 204; the third material layer, the second material layer 204, the first bonding material layer 203, the second bonding material layer 201 and the first material layer 202 are etched to form the transduction device.
The material of the third layer 301 includes a metal or metal nitride, and the metal includes titanium, nickel, molybdenum, copper, platinum, or the like; the metal nitride comprises titanium nitride.
In this embodiment, the density of the material of the third layer 301 is greater than the density of the material of the second layer 208. The material of the diffusion preventing layer 301 can prevent electromigration of aluminum atoms of the material of the second layer 208 at the surface.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.
Claims (20)
1. A transducer assembly on a surface of a piezoelectric substrate, comprising:
the electrode strips are arranged in parallel along a first direction, the electrode strips comprise a first layer and a second layer positioned above the first layer, the average diameter of first grains in the first layer is smaller than that of second grains in the second layer, the first layer is close to the piezoelectric substrate and is used for inhibiting vibration migration, the material of the second layer comprises aluminum copper alloy, the second layer is used for inhibiting electromigration, and the piezoelectric substrate and the second layer are respectively positioned on two sides of the first layer;
alternatively, the electrode strip includes a first layer, a second layer above the first layer, and a third layer above the second layer, wherein an average diameter of first grains in the first layer is smaller than an average diameter of second grains in the second layer, the first layer is close to the piezoelectric substrate and is used for inhibiting vibration migration, a material of the second layer includes aluminum copper alloy or aluminum, a density of the material of the third layer is greater than a density of the material of the second layer, the third layer is used for inhibiting electromigration, the piezoelectric substrate and the second layer are respectively located on two sides of the first layer, and the first layer and the third layer are respectively located on two sides of the second layer.
2. The transducer device according to claim 1, wherein the yield strength of the first layer of material is greater than the yield strength of the second layer of material.
3. The transducer device of claim 1, wherein the resistivity of the first layer of material is greater than the resistivity of the second layer of material.
4. The transducer device according to claim 1, wherein the material of the first layer comprises an aluminum-neodymium alloy, wherein the atomic percentage content of neodymium atoms in the aluminum-neodymium alloy is 1% -8%.
5. The transducer device according to claim 1, wherein the material of the second layer comprises an aluminum-copper alloy, wherein the atomic percentage content of copper atoms in the aluminum-copper alloy is 0.5% -4%.
6. The transducer device according to claim 1, wherein the material of the third layer comprises a metal or a metal nitride; wherein the metal comprises titanium, nickel, molybdenum, copper or platinum; the metal nitride comprises titanium nitride.
7. The transducer device according to claim 1, wherein the thickness of the first layer is less than or equal to 50% of the thickness of the electrode strip.
8. The transducer device of claim 1, wherein the electrode strip further comprises: a first bonding layer between the first layer and the second layer.
9. The transducer device of claim 8, wherein the material of the first bonding layer comprises a metal or a metal nitride; wherein the metal comprises titanium, titanium tungsten alloy or nichrome; the metal nitride comprises titanium nitride.
10. A surface acoustic wave resonator device comprising:
a piezoelectric substrate;
a transducer according to any one of claims 1 to 9, located on the piezoelectric substrate.
11. The surface acoustic wave resonator apparatus of claim 10, wherein the electrode strip further comprises: and a second bonding layer located between the piezoelectric substrate and the first layer.
12. The surface acoustic wave resonator device of claim 11, wherein the material of the second bonding layer comprises a metal or a metal nitride; wherein the metal comprises titanium, titanium tungsten alloy or nichrome; the metal nitride comprises titanium nitride.
13. A filtering apparatus, comprising:
a number of surface acoustic wave resonator devices as claimed in any one of claims 10 to 12.
14. A method of forming a surface acoustic wave resonator device, comprising:
providing a piezoelectric substrate;
forming a transduction device on the piezoelectric substrate, the transduction device comprising: a plurality of electrode bars disposed in parallel along a first direction parallel to a surface of the piezoelectric substrate, wherein the electrode bars comprise: a first layer and a second layer over the first layer, the first layer having an average diameter of first grains smaller than an average diameter of second grains in the second layer, the first layer for inhibiting vibration migration, the second layer comprising a material of aluminum-copper alloy, the second layer for inhibiting electromigration;
alternatively, the electrode strip includes a first layer, a second layer over the first layer, and a third layer over the second layer, the first layer having an average diameter of first grains smaller than an average diameter of second grains in the second layer, the first layer being for inhibiting vibration migration, the second layer material including an aluminum-copper alloy or aluminum, the third layer material having a density greater than a density of the second layer material, the third layer being for inhibiting electromigration.
15. The method of forming a surface acoustic wave resonator device of claim 14 wherein the yield strength of the first layer material is greater than the yield strength of the second layer material.
16. The method of forming a surface acoustic wave resonator device of claim 14 wherein the resistivity of the first layer of material is greater than the resistivity of the second layer of material.
17. The method of forming a surface acoustic wave resonator device of claim 14, wherein forming a plurality of the electrode strips comprises: forming a first material layer over a piezoelectric substrate; forming a second material layer over the first material layer; and patterning the second material layer and the first material layer to form a plurality of electrode strips.
18. The method of forming a surface acoustic wave resonator device of claim 17 wherein forming a plurality of the electrode strips further comprises: forming a first bonding material layer before forming the second material layer, wherein the first bonding material layer is positioned on the first material layer, and the second material layer is positioned on the first bonding material layer; patterning the first bonding material layer to form a first bonding layer between the first layer and the second layer.
19. The method of forming a surface acoustic wave resonator device of claim 17 wherein forming a plurality of the electrode strips further comprises: forming a second bonding material layer before forming the first material layer, wherein the bonding material layer is positioned on the piezoelectric substrate, and the first material layer is positioned on the second bonding material layer; and patterning the second bonding material layer to form a second bonding layer between the first layer and the piezoelectric substrate.
20. The method of forming a surface acoustic wave resonator device of claim 17, wherein forming the third layer comprises: forming a third material layer before patterning the second material layer and the first material layer, wherein the third material layer is positioned on the second material layer; patterning the third material layer to form a third layer on the second layer.
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| JP2005229566A (en) * | 2004-01-15 | 2005-08-25 | Seiko Epson Corp | Surface acoustic wave device and manufacturing method thereof |
| JP2005347892A (en) * | 2004-05-31 | 2005-12-15 | Fujitsu Media Device Kk | Surface acoustic wave element |
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| JP4279271B2 (en) * | 2005-06-01 | 2009-06-17 | アルプス電気株式会社 | Surface acoustic wave device and manufacturing method thereof |
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